Starting fzf at a given cursor position?

[Kabouik]

I am writing a script whereby pressing right enters a directory, and left does a cd to the parent directory and lists fzf items with fd again. Since left actually feels like a "Go back to the parent folder" key after entering a directory, I would like it to remember the position of the directory that was explored in the first place.

Unfortunately, I don't think I can save FZF_POS when entering the folder and then use the pos($FZF_POS) action when going back because the action would be triggered on a new key press, while in my case when I press left, there's a new round of fd <args> | fzf before showing the list again.

I have tried start:pos($FZF_POS)" (see below), but no luck. Is there a trick I could use?

main() {
    while :; do
	clear
	cd "$dir"
	selection=$(fd .  \
			| fzf --query "${tmp}" \
                              --bind="start:pos($FZF_POS)" \
			      --bind="left:execute(echo 'cdup' > /tmp/fzplayer-arg)+accept" \
			      --bind="right:execute(echo 'cddown' > /tmp/fzplayer-arg)+accept")

	if [[ -f "/tmp/fzplayer-arg" ]]; then
            arg=$(cat /tmp/fzplayer-arg)
            rm /tmp/fzplayer-arg
        fi

        if ! [[ -v "$selection" ]]; then
            clear
            case "$arg" in
                cddown)
		    # cd into selected directory and relaunch main()
                    dir="$(realpath "$selection")"
		    continue
                    ;;
                cdup)
		    # cd into parent directory and relaunch main()
		    if [[ "$(realpath "$dir")" == "$(realpath "$media")"* ]]; then
			dir="$(dirname "$dir")"
		    fi
                    continue
                    ;;
            esac
        fi
    done
}